If you know what a sharp graver looks and feels like then you will know how to sharpen it. You don't need any of the "holders" persay to be able to sharpen a graver. If you know what you are looking for you can sharpen by hand.
I have taken several engraving classes. One from Wallace, one from Mark Silver, a couple of GRS classes and I spent a week with Sam Alfono.
From all this I learned that you cannot engrave until you learn to sharpen and I also learned that all of these instructors sharpen differently.
When I first started trying to engrave I started with Meeks book which has a lot of good info but I struggled with trying to sharpen the way he explains how to sharpen. After struggling for about 3 years I decided to take the beginners class from GRS. It was the best money I ever invested. The first thing I learned was how to sharpen a 90 degree square graver. I was also introduced to their Dual Angle Shapening fixture. With this fixture I could consistantly sharpen a graver. With this fixture you can shapen many different types of gravers, the square graver in varying degree cuts, 90 to 120 degree being the common ones. Flat gravers, round and many custom gravers that you will develope as you gain experience.
I also invested in the Lindsay Universal Sharpening Template. This template gives a 116 degree V graver with what Steve calls a paralel heel. This is a different heel than the standard heel that is commonly made on a standard heeled square graver.
You get no heel drag with the paralel heel.
In Mark Silver's class he taught to sharpen a 90 degree square with the standard heel.
In Wallace's class he also taught to sharpen the same as Mark but I noticed that his graver was sharpened similar to Steve's Lindsay's Paralel heeled graver. Wallace also shapened this graver by hand with no tool holder. He would just lean the graver against the bench and touch up the heel with a good stone.
Now Walace had developed his graver to suit him and how he engraved which was well suited to hammer and chisel engraving.
Somehow you have to gain the knowledge that is needed to understand what I have stated here. Not trying to belittle anyone. You can every graver sharpener out there but if you don't know what you are looking for in a sharp graver then you just have a collection on graver sharperens.
The best information out there on graver sharpening is Sam Alfono's CD on graver sharpening. It is worth the money, he covers all the common types of gravers and how to sharpen them. He uses the GRS dual angle sharpening fixture. He does not cover the Linsay template.
I found that I enjoyed engraving much more once I gained the knowledge of what a sharp graver was. Now with that said I am still learning to engrave and developing my skill, I am in no way an expert. I do know you will never cut a good or straight line with a dull or improperly sharpened graver.
